An existing biometric authentication device executes a biometric authentication process by picking up an image of a subject with the use of a dedicated image pickup device such as an infrared camera or the like, and by determining whether biological information extracted from the picked-up image and preregistered biological information match.
Incidentally, biometric authentication devices provided with a general-purpose image pickup device are expected to command a large market share hereafter due to the recent trend of decreasing prices for biometric authentication devices. For example, as a general-purpose image pickup device, an image pickup device provided with a single-chip image pickup element, RGB color filters of a Bayer arrangement, and the like is conceivable. Moreover, a demosaicking process is executed for a signal indicating luminance values of pixels of an image picked up by such an image pickup device so as to reduce a sampling noise caused by a difference among frequency bands of light rays that pass through the color filters, an imbalance among light absorption characteristics of the color filters, or the like (for example, see Japanese Laid-open Patent Publication No. 2011-143100).
Additionally, shapes of veins are sometime used as biological information for biometric authentication. In this case, a luminance value of a portion that exhibits the veins in a picked-up image is smaller than that of a portion peripheral to the veins due to the light absorption characteristic of reduced hemoglobin within blood, and a change in the luminance value is smaller than that in the portion peripheral to the veins. Accordingly, when a demosaicking process is executed for an image including the veins, low-frequency components can be possibly reduced along with a sampling noise, leading to a possible difficulty in extracting the shapes of the veins as biological information from the image for which the demosaicking process has been executed.